Expendable radiosonic buoy



Feb. 17, I. MASQN EI-AL EXPENDABLE RADIOSONIC BUOY Filed Sept. 21, 1944i 2 SHEETSSHEET l (9 0 BATTERY 35 PACK-l8 T Z4- Z4 20 .g I. [a

FOR/M010] I6 TRANSMITTER umr HYDROPHONtj UNIT I9 I5 a wm'vtow RUSSELLMASON JOSEPH A BARKSON JAM ES (1 NC NARY T/Zifi 2 Guam Feb. 11, 1953 RMASON HAL 2 9,083

EXPENDABLE RADIOSONIC BUOY Filed Sept. 21, 1944 2 SHEETS-SHEET 2 34- TORADIO TRANSMITTER WATER L/ I III ll/ RUSSELL l MASON JOSEPH A BARKSONJAMES C MC NARY UNITED STATES Patented Feb. 17, 1953 EXPENDABLERADIOSONIC BUOY Application September '21, 1944, Serial No. 555,154

ATENT OFFICE 6 Claims.

This invention relates in general to signalling apparatus and isdirected in particular to improvements in radio-sonic buoys.

Buoys of the class described are provided with a rather small radiotransmitter unit and an antenna. Hung below the buoy in the water is amicrophone which is electrically connected to the input of the radiotransmitter. Any submarine signals picked up by the microphone functionto modulate the radio transmitter and such modulated signals arebroadcast to suitable receiver apparatus tuned to the transmitterfrequency and located at a suitable station. The station which may be onshore, on aircraft, or on a vessel is thus warned of the presence of thesubmarine signals. The device has special utility in detecting thepresence of submarines by picking up the sounds made by theirpropellers.

scription to follow and from the accompanying drawings in which:

Figs. 1A and 1B are elevation views, partly in section, showing thecomplete buoy prior to being launched from an aircraft;

Fig. 2 is an enlarged top plan view of the buoy shown in Figs. 1A and1B.

Fig. 3 is an enlarged vertical section taken on lines 3--3 of Fig. 2;

Fig. 4 is an enlarged section taken on lines Fig. 5 is a view showingthe buoy during its Referring now to the drawings, the radio-sonic buoyincludes a casing In which is essentially a hollow cylinder closed atthe top and open at the bottom. Casing in which may be made of thingauge metal sheeting or pressed paper is divided into upper and lowercompartments ll 4-4 of Fig. 2; and

descent.

When these buoys are used in naval operations such as for example withconvoys, it is highly necessary that steps be taken to prevent them fromfalling into the hands of the enemy. Accordingly, it has been thepractice to provide the buoy with an air filled chamber sealed againstthe water by a water-soluble plug. Thus after a predetermined time inthe water, the plug becomes completely dissolved, allowing water toenter the chamber to replace the air which was in it. The dimensions ofthe chamber are so selected that when it becomes filled with water, thebuoy no longer has a positive buoyancy and consequently sinks to thebottom.

The general object of this invention is to provide a highly improvedconstruction for a radiosonic buoy of the type described which isparticularly adapted to be launched into the water from aircraft byparachute.

One specific object is to provide a construc tion in which the watersoluble plug above described is automatically readied for use when thebuoy is launched.

Another specific object is to rovide for automatically placing the radiotransmitter in operative condition as the buoy is launched.

A further object is to provide a novel construction for cushioningimpact of the buoy as it strikes the water.

Still another object is to provide a novel construction for the upperend of the buoy which serves a threefold function of supporting theparachute pack, enclosing and protecting the antenna, and insulating thelatter from the water when the buoy is in floating position.

These and other objects of the invention will become more apparent fromthe detailed deand !2, respectively by a watertight partition member l3which may be made of wood.

A plurality of platforms 14, I5 and I6, superimposed upon each other andarranged transversely of the longitudinal axis of buoy casing It! andlocated in the upper compartment II, are adapted to support a radiotransmitter unit. The transmitter unit preferred is of conventionalconstruction operating on the well known principle of frequencymodulation. The construction details of this unit form no part of thisinvention and hence in the interest of simplicity, it has not been shownin the drawings. Sufilce to say for purposes of this invention,separable component parts of the transmitter unit are supported on eachof the transverse platforms. These platforms may be resiliently mountedwith respect to the buoy casing Hi by any well known mounting means suchas, for example, rubber bushings (not shown).

Also disposed in the upper compartment H and located beneath theplatform 44 is a considerable volume of crepe wedding ll which isutilized to provide in part the proper amount of buoyancy for thecomplete buoy so that the latter will float in a vertical positon in thewater with the water line just above the top of the casing l9. Anothercomponent of the total buoyant effect is providedby air which isreleasably entrapped in compartment II by means which will be describedhereinafter.

Disposed beneath the crepe wadding H is a battery pack. l8 whichsupplies the necessary power for the radio transmitter unit.

The lower compartment [2 contains a hydrophone unit l9 that includes acylindrical, sound 3 transparent casing, and within which is located ahydrophone. This hydrophone has an omnidirectional characteristic andhence detects any compressional wave energy which may be incom ing fromany direction around the underwater horizon.

The hydrophone per so may be of known construction such as, for example,the magnetostriction unit shown and described in application Serial No.518,447, filed January 15, 1944, by Albert L. Thuras, now Patent2,472,388.

It will be noted that the upper end .of the easing of hydrophone unit [9is provided with a tubular neck portion around which is coiled aconsiderable length of conductor cable .20 which electrically connectsthe hydrophone unit to the input of the radio transmitter unit. Thisneck portion is received by a centrally located depending boss gl onpartition I3. By this arrangement, the upper end of the hydrophone unitHi is held firmly in position.

The construction of the casing for hydrophone unit I9 and its associatedconductor cable 2t is more particularly described and claimed inapplication Serial No. 535,170, filed May 11, 1944, by Russell I. Masonet a1.

At the bottom of the lower compartment I2 there is located a pressureoperated release mechanism 22 which functions upon impact of the bottomof the buoy casing II] with the water to release the hydrophone unit I 9from the position shown allowing it to drop out of casing ill anddescend through the water until conductor cable 28 has paid out. Thepressure operated release mechanism 22 includes a spring 23 which bearsagainst and holds the bottom end of hydrophone unit l9 firmly when itoccupies the position shown in Fig. 1B. The details of construction ofthe release mechanism 22 form per se no part of this invention and arenot claimed herein.

It will be noted that buoy casing In at the top of the lower compartment[2 is provided with two or more apertures 24. However, one such aperturemay be suflicient. Apertures 24 serve as exhaust ports for the air thatwould otherwise be entrapped within compartment [2 when the buoy strikesthe water in its vertical position, thereby reducing considerably theimpact forces which are set up at such time.

The top wall of buoy casing ID may be integral with the side wall but itis preferred that it be constituted by a wooden cap member 25 in whichis provided a central opening 26 and through which is secured a threadedstud 21. A multi-seciton telescoping antenna 28 is utilized on the buoyand at thebottom of the outermost section there is welded or otherwisesecured thereto a nut 29. The antenna is fixed in position on the buoyby screwing the nut 29 down upon stud member 21 in the manner shown inFig. 3. A tube 3! of insulating material such as fibre surrounds antenna28 and fits down into a recessed portion in the top of cap member 25. Amuch shorter and tapered tubular member 32, also of insulating material,fits within tube 3i, and is internally threaded so as to enable it to bescrewed down upon external threads provided on the outermost section ofthe telescoping antenna 28. However, if desired, tubes 3i and 32 may beintegrated into a'single tube.

Surrounding tube 3| is a parachute pack 33, at the bottom of which islocated an annular member 34 which is adapted to make a press fit withrespect to tube 3] so that the pack will be held securely in position ontube 31 when in the position shown in Fig. 3.

The construction of parachute pack 33 per se forms no part of thisinvention and hence has not been shown in detail. However, it will beseen from Fig. v 2 that the pack is provided with a plurality of pairsof shroud lines 35 and a static line 36. Each pair of the shroud linesis secured to cap member 25 by means of screws 31 and the static line 35may be secured to the wall of casing H! by gummed tape 38, see Fig. 1A.

To facilitate manufacture, parachute pack 33 and tube 3| may constitutea single unit which is then mounted in the position shown in Fig. 3 byslipping it over the telescoped antenna 28 which has previously beenscrewed into the position shown and then threading down tube 32 so thatan external shouldered portion 39 on tube 3?; presses down tightlyagainst the top edge of tube 3!. In this manner, antenna 28, tube 31 andparachute pack 33 are all secured firmly in position on cap 25 of thebuoy casing Ill.

Referring now to Figs. 2 and 4, cap member 25 of the buoy casing isprovided with a stepped aperture 4| which is adapted to receive a watersoluble plug 42 made of any suitable material such as carbowax. Afterthe buoy has been dropped into the water, its buoyancy is such that itfloats in a vertical position with the water line just above the top ofcap 25. As the buoy remains in the water, the carbowax plug 42 gradually dissolves and, after a predetermined length of time, which dependsupon the cross sectional area and length of plug 42, water will flowinto the upper compartment ll of the casing is through the opening 41,displacing the air in compartment ll. The buoy construction is such thatthis is sufficient to create a condition of negative buoyancy relativeto the water with the result that the buoy will sink. This arrangementis provided to prevent the device from coming into the hands of theenemy after it has served its purpose. Prior to launching of the buoy,plug 42 is sealed against moisture by a stopper 3. This stopper containsa transverse opening through which is passed one of the para chutelines, preferably the static line 36. Thus just prior to launching, asthe static line is pulled, stopper 4% will be automatically removed,readying plug d2 for its function.

Cap 25 is also provided with a recess it within which is received aswitch 35. Switch es includes a fixed contact member 46, movable contactmember 4'! anda switch contact operator consisting of a pin 48 whichwhen inserted to the position shown in Fig. 4 separates contact members45 and 41.

It will be seen from Fig. 2 that one of the shroud lines to theparachute passes through an opening 49 in the pin it. Consequently, whenthe buoy is launched and the parachute pack 33 opens, pin 44 will bepulled out from the position shown in Fig. 4 as the shroud line 35tightens allowing switch contacts d6, ii to close. This completes acircuit from the battery pack M3 to the radio transmitter unit andplaces the latter in an operative condition.

It is desired to point out that while in the preferred embodiment of theinvention, the static line 36 is passed through stopper 43 and one ofthe shroud lines 35 is passed through switch pin is in order to placethe buoy in service with the least possible number of separateoperations, the same benefitsmay obviously b obt i by using only thestatic line 36 or the shroud lines 35 for removing the stopper 43 andpin 48.

Operation When it is desired to launch the radio sonicbuoy, the operatorpulls the telescoped sections of antenna 28 outwardly to their extendedposition. He then breaks loose the static line 38 by tearing off tape33. As previously explained, a pull on static line 35 removes stopper13. Continued pull on line 36 then removes an outer protective casingaround the parachute which thereby releases about a fifteen foot lengthof line which theretofore had been coiled within the outer protectivecasing. Now holding on to the loop at the end of static line 33 orotherwise securing it, the operator launches the buoy, as for exampleover the side of an aircraft. As the static line tightens, an innerprotective cover around the parachute folds is pulled off, after whichthe static line is broken by means of a weak link and the parachute thenunfolds to catch the air. As the parachute shroud lines 35 tighten, pin43 will be pulled out thus automatically turning the radio transmitteron. The

buoy then descends in a vertical position as shown in Fig. 5 and, as itstrikes the water, the impact forces cause the release mechanism 22 tooperate thereby releasing the hydrophone unit it from its positionwithin compartment :2 and allowing it to drop down into the water belowthe buoy casing and there be suspended by the conductor cable 20.

As the buoy casing floats vertically in the water with the water linejust above cap member 25, the parachute collapses around the insulatortube 3 l the parachute having a central opening therein large enough topermit this.

If a submarine is in acoustic range of the hydrophone Hi, the underwatercompressional wave energy emitted by the submarines propellers will betranslated into electrical energy by the hydrophone and such energy willthen be fed over conductor cable 28 into the input of the radiotransmitter unit, causing the latter to send out frequency modulatedsignals. These signals are then picked up on a suitable receiver carriedon the aircraft and the operator will then know that a submarine islocated in the vicinity of the buoy.

When plug 42 has dissolved, Water will enter the upper compartment H andthe buoy will then sink leaving no trace.

In conclusion, while the described embodiment of this invention is to bepreferred, it is to be understood that various changes may be made inthe detailed construction without departing from the spirit and scope ofthe invention as defined in the appended claims.

Having thus fully described our invention, we claim:

1. A radio-sonic buoy comprising a casing designed to be dropped towardsthe water in a vertical position, a partition member dividing saidcasing into upper and lower compartments, a radio transmitter unit insaid upper compartment, and a hydrophone releasably supported withinsaid lower compartment, said lower oompartment being open at the bottomand being provided with at least one aperture through the casing wall tovent air as said buoy casing strikes the water and thereby lessen impactshock.

2. A buoy device adapted to be launched from aircraft comprising acasing, signalling apparatus in said casing, a parachute pack attachedto said casing for dropping it into the water, a water soluble plugsealing an aperture in the buoy casing, said aperture being disposedbelow the water line of the casing and leading into a compartmentnormally having a gas entrapped therein, a stopper for sealing the topof said plug, and means connecting said stopper to a line of saidparachute pack to effect its removal automatically.

3. A buoy device adapted to be launched from aircraft comprising acasing, signalling apparatus in said casing, a telescoping antennaconnected to said signalling apparatus, means securing said antenna onsaid casing, an insulator tube surrounding said antenna, and a parachutepack surrounding and supported by said insulator tube, and designed sothat when it is open and the antenna is extended the latter projectscentrally through the opened parachute.

4. A buoy device adapted to be launched from aircraft comprising acasing, signalling apparatus in said casing, a telescoping antennaelectrically connected to said signalling apparatus, means securing saidantenna on said casing, an insulator tube surrounding said antenna whentelescoped, means securing said insulator tube to said antenna, and aparachute pack surrounding and. supported by said insulator tube.

5. In a buoy of the class described, a muitisection telescoping antennathe outer section of which is threaded at its upper end, means at thebase of said antenna for securing it upon said buoy, an insulator tubesurrounding said antenna, said tube being internally threaded forengagement with the threaded portion of said antenna to thereby securesaid tube in position, and a parachute pack surrounding and supported bysaid insulator tube.

6. In a signalling device adapted to be launched from aircraft includinga radio transmitter, a power supply unit therefor, and a parachute packattached to said device, means for placing said radio transmitter unitin operative condition comprising, a switch having contacts connectingsaid power supply unit to said radio transmitter, a telescopic antennaelectrically connected to said transmitter so as to transmit a signalwhen said transmitter is in operative condition, operating means forsaid switch contacts, and means connecting said switch contact operatingmeans to a line of said parachute pack to effect automatic operation byopening of the parachute.

RUSSELL I. MASON. JOSEPH A. BARKSON. JAMES C. MCNARY.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 1,154,272 Sanger et al. Sept. 21,1915 1,308,003 Elia June 24, 1919 1,423,337 Sperry Aug. 15, 19221,430,162 Elia Sept. 26, 1922 1,754,134 Wiley 8, 1930 2,310,017 CanonFeb. 2, 1943 2,361,177 Chilowsky Oct. 24, 1944 FOREIGN PATENTS NumberCountry Date 596,439 Germany May 3, 1934 335,125 Italy Feb. 1, 1936

